The Microbiological Characteristics of Associated With Early Mortality in Patients With Bloodstream Infection.

Background: Despite rapid deaths resulting from bacteremia, the clinical impact of the microbiological characteristics of strains on early mortality (EM) is unclear. We aimed to identify the microbiological characteristics of strains associated with EM.

Methods: Clinical information and isolates from patients with bacteremia from January 2015 to December 2021 were collected. EM was defined as death within 3 days of the initial positive blood culture, whereas late mortality meant death within 5-30 days. The microbiological characteristics of were analyzed using multilocus sequence typing, polymerase chain reactions, and a in vivo infection model.

Results: Among 130 patients, 69 (53.1%) died within 30 days and EM occurred in 38 (55.1% of 30-day deaths). Sequence type 191 (ST191) strain was more prevalent in patients with EM than in 30-day survivors (31.6% vs 6.6%). Regarding virulence genes, was more frequent (92.1% vs 47.5%), whereas was less frequent (13.2% vs 52.5%) in patients with EM than in 30-day survivors. Higher clinical severity, pneumonia, and ST191 infection were identified as independent risk factors for EM. In the infection model, ST191, +, and - isolates showed higher virulence than non-ST191, -, and + isolates, respectively.

Conclusions: ST191 and were more frequently found in the EM group. ST191 infection was also an independent risk factor for EM and highly virulent in the in vivo model. Tailored infection control measures based on these characteristics are necessary for bacteremia management.